What is Antimatter?

Antimatter sounds like the stuff of science fiction, but it’s very real. It is, however, elusive.

Antimatter particles are subatomic particles with properties opposite those of normal matter particles. So a positron (positively charged) is the antiparticle equivalent of the electron (negatively charged). When a particle and its antiparticle meet, they annihilate (are destroyed), releasing a lot of energy.

Antimatter particles are created in ultra high-speed collisions. There was a lot of it after the Big Bang. But today antimatter is rare.1

How rare is antimatter? Lawrence Krauss puts it this way:

I like to say that while antimatter may seem strange, it is strange in the sense that Belgians are strange. They are not really strange; it is just that one rarely meets them.2

In the sentences before making that statement, Krauss tells us something interesting about antimatter:

Because antiparticles otherwise have the same properties as particles, a world made of antimatter would behave the same way as a world of matter, with antilovers sitting in anticars making love under an anti-Moon. It is merely an accident of our circumstances, due, we think, to rather more profound factors…that we live in a universe that is made up of matter and not antimatter or one with equal amounts of both.3

That’s pretty awesome! You might be wondering then, how can we know that this universe is made of matter and not antimatter? If they behave the same way, how can we tell the difference? Antimatter has an opposite charge and quantum spin4; those are the subtle differences that let us know that we live in a universe comprised of matter. Well, there’s that and the possibility that it falls up.5

Every particle in existence has an antiparticle equivalent, which is almost identical except it carries the opposite electric charge. Matter is composed of normal particles and antimatter is composed of antiparticles—for example, while a proton and an electron form an ordinary hydrogen atom, an antiproton and a positron form an antihydrogen atom. Antimatter is created all the time in high-energy collisions, like when cosmic rays impact Earth’s atmosphere, but it immediately disappears because when matter and antimatter collide, they annihilate in a flash of pure energy. This makes it difficult to study experimentally, and neither can we find any evidence of a significant concentration of antimatter in the wider universe. The universe we know is dominated by ordinary matter—it makes up every person and planet and star—and yet if matter and antimatter were created equally at the birth of the universe, where has all the antimatter gone? This asymmetry is a perplexing question in physics, and several theories have been proposed to explain it. Perhaps nature favours matter reactions over antimatter ones; or perhaps matter and antimatter particles decay differently; or perhaps there are far flung regions composed primarily of antimatter, but they’re just beyond our visible universe. Researchers are currently trying to determine if such regions exist by studying colliding superclusters for high-energy signatures of annihilation, and by studying decay patterns in quarks.

Top 10 Strangest Things in Space

The universe is a weird place. Here’s a look at some of the strangest things in the cosmos.

1. Antimatter

Like Superman’s alter-ego, Bizzaro, the particles making up normal matter also have opposite versions of themselves. An electron has a negative charge, for example, but its antimatter equivalent, the positron, is positive. Matter and antimatter annihilate each other when they collide and their mass is converted into pure energy by Einstein’s equation E=mc2. Some futuristic spacecraft designs incorporate anti-matter engines.

2. Mini-Black Holes

If a radical new “braneworld” theory of gravity is correct, then scattered throughout our solar system are thousands of tiny black holes, each about the size of an atomic nucleus. Unlike their larger brethren, these mini-black holes are primordial leftovers from the Big Bang and affect space-time differently because of their close association with a fifth dimension.

3. Cosmic Microwave Background

Also known as the CMB, this radiation is a primordial leftover from the Big Bang that birthed the universe. It was first detected during the 1960s as a radio noise that seemed to emanate from everywhere in space. The CMB is regarded as one of the best pieces of evidence for the theoretical Big Bang. Recent precise measurements by the WMAP project place the CMB temperature at -455 degrees Fahrenheit (-270 Celsius).

4. Dark Matter

Scientists think it makes up the bulk of matter in the universe, but it can neither be seen nor detected directly using current technologies. Candidates range from light-weight neutrinos to invisible black holes. Some scientists question whether dark matter is even real, and suggest that the mysteries it was conjured to solve could be explained by a better understanding of gravity.

5. Exoplanets

Until about the early 1990s, the only known planets in the universe were the familiar ones in our solar system. Astronomers have since identified more than 500 extrasolar planets (as of November 2010). They range from gargantuan gas worlds whose masses are just shy of being stars to small, rocky ones orbiting dim, red dwarfs. Searches for a second Earth, however, are still ongoing. Astronomers generally believe that better technology is likely to eventually reveal worlds similar to our own.

6. Gravity Waves

Gravity waves are distortions in the fabric of space-time predicted by Albert Einstein’s theory of general relativity. The gravitational waves travel at the speed of light, but they are so weak that scientists expect to detect only those created during colossal cosmic events, such as black hole mergers like the one shown above. LIGO and LISA are two detectors designed to spot the elusive waves.

7. Galactic Cannibalism

Like life on Earth, galaxies can “eat” each other and evolve over time. The Milky Way’s neighbor, Andromeda, is currently dining on one of its satellites. More than a dozen star clusters are scattered throughout Andromeda, the cosmic remains of past meals. The image above is from a simulation of Andromeda and our galaxy colliding, an event that will take place in about 3 billion years.

8. Neutrinos

Neutrinos are electrically neutral, virtually mass-less elementary particles that can pass through miles of lead unhindered. Some are passing through your body as you read this. These “phantom” particles are produced in the inner fires of burning, healthy stars as well as in the supernova explosions of dying stars. Detectors are being embedded underground, beneath the sea, or into a large chunk of ice as part of IceCube, a neutrino-detecting project.

9. Quasars

These bright beacons shine to us from the edges of the visible universe and are reminders to scientists of our universe’s chaotic infancy. Quasars release more energy than hundreds of galaxies combined. The general consensus is that they aremonstrous black holes in the hearts of distant galaxies. This image is of quasar 3C 273, photographed in 1979.

10. Vacuum Energy

Quantum physics tells us that contrary to appearances, empty space is a bubbling brew of “virtual” subatomic particles that are constantly being created and destroyed. The fleeting particles endow every cubic centimeter of space with a certain energy that, according to general relativity, produces an anti-gravitational force that pushes space apart. Nobody knows what’s really causing the accelerated expansion of the universe, however.

A Black Hole Doesn’t Die — It Does Something A Lot Weirder

Black holes are basically “game over, man,” for anything that gets too close to them, but they aren’t invincible. In fact, they’re always in the process of self-destructing. We’ll look at how they fizzle out, and see if we can help them do it faster.

The Event Horizon

Realistically speaking, you are dead as soon as you get anywhere near a black hole. You’ll be snapped like a rubber band by the differences in the gravitational pull on your top and bottom half, or you’ll be fried by radiation (more on that later). No one in the foreseeable future (even if we try to foresee multiple millennia into the future) will get close to a black hole. Pass the event horizon, however, and you don’t even have an unforeseeable future. Once material gets beyond the event horizon, it’s being pulled into the black hole with such force that it doesn’t escape. Not even light gets out. Once something has gone beyond the event horizon, it no longer really “counts” as part of the universe anymore.

For a high school science fair project, seventeen-year-old Michio Kaku built a particle accelerator in his parent’s garage that was able to generate a magnetic field 20,000 times greater than the Earth’s and produce collisions powerful enough to create antimatter.

Black holes and pulsars radiate thick jets of particles, comprised of electrons and their anti-particle partner – the positron. Astronomers are able to observe the jets but are unable to directly study and analyze them due to their distant locations in the universe. The exact particle composition and energy content of the jets remains a mystery. With the help facilities such as CERN, physicists are able to smash particles together in an attempt to understand the fundamental particles seen in these cosmic jets and plasma.

For every particle in our universe, there is an equal and opposite particle called an anti-particle with positrons being the anti-particle of electrons. Until recently, the only way to mass produce and analyze such particles was by means of vast underground particles accelerators like the Large Hadron Collider (LHC); however, thanks to a team of researchers at the University of Texas, the LHC’s capabilities are now available in a more convenient desktop version. An international team of physicists from the University of Michigan have gone one step further and developed an “anti-matter gun”, approximately one meter in length and capable of generating short bursts of positrons and electrons just like the ones emanating from black holes.

To create these particle bursts, the team ionized a sample of inert helium gas by firing a petawatt (quadrillion watt) laser beam at it, generating a high-speed electron stream. The electron stream was then focused on super thin sheets of copper, tin, tantalum and lead, causing them to collide with individual metal atoms and yielding a stream of shorter, denser bursts of electrons and positrons, than typically produced by larger particle accelerators. Simply stated, the team used a quadrillion watt laser, fired it for approximately thirty quadrillionths (30 femtoseconds) of a second and produced quadrillions of positrons – statistics comparable to CERN!

The new laser-based “anti-matter gun” is one of the only methods able to produce jets and plasma bursts simultaneously, enabling the team to directly observe and analyze how the particle jets and plasma interact. Researchers are optimistic these new results will lead to better understanding of anti-matter, black holes and the jets they produce.

The image seen here is an artist impression of particle jets emanating from a black hole.

Hawking radiation mimicked in the lab

Scientists have come closer than ever before to creating a laboratory-scale imitation of a black hole that emits Hawking radiation, the particles predicted to escape black holes due to quantum mechanical effects.

The black hole analogue, reported in Nature Physics1, was created by trapping sound waves using an ultra cold fluid. Such objects could one day help resolve the so-called black hole ‘information paradox’ - the question of whether information that falls into a black hole disappears forever.

Could you imagine if there’s an alternate universe out there somewhere where there’s another you? An evil you perhaps with a twirly moustache?

There are plenty of hypothesis’ arguing for this reality, one of the most popular being string theory.

I need to stop right in the middle of an exciting topic and be real: There’s VERY LITTLE EVIDENCE for this. Even the strongest piece of evidence which I’m about to talk about, isn’t what one would call a “smoking gun”.

Now to go totally against what I just said. If you look at what was being said back in 2007, and got the opinion on string theory and multiverses from the popular science community, you’d have gotten a sigh and speech on how there’s no evidence for the multiverse.

Not true. There is a single piece of evidence that had been predicted, tested and found to be true. Enter, the Bubble Multiverse.

Think about the big bang. Who’s to say that the big bang could only happen once? If it turns out that something existed before the Big Bang (which of course science presumes so as nothingness is unprovable) who’s to say that in the pre-big bang universe, there couldn’t have been multiple big bangs? This is the idea.

In that pre-big bang cosmos, multiple big bangs could’ve happened. They would all be similarly expanding in space just like ours. This can be imagined like a series of bubbles or balloons growing as air is pumped in. Each bubble would have on it’s spreading surface, a universe. Each could run by different physical laws then ours, perhaps by a small degree and some by a huge amount.

The evidence for this? Astronomers in London have predicted that the eternal expansion of each of these universes would result in some of them eventually colliding with the other and that this would result in visible bruising on the Cosmic Microwave Background, a measure of heat from the time of the Big Bang. They found this bruise. I’m linking an article citing two published scientific papers (peer reviewed) right here if you’re interested in doing the detective work yourself.

It’s pretty important to note that with the sheer size of data contained in the Cosmic Microwave Background it’s possible to extrapolate almost any sort of thing and claim it as evidence of practically anything. Why then do I say this is still legitimate evidence? Because it was predicted, tested and found within the parameters of the only theory we have: string theory. This is for all intents and purposes the only game in town when it comes to a unification of quantum mechanics and general relativity.

So on one hand yes, it’s our best possible conclusion so far that there are multiple universes, but on the other hand, we know full well that it’s based on sparse, tentative and speculative evidence.

Stop here if you don’t want the frightening part.

What would it mean if the Bubble Multiverse is real? This is where shit gets creepy. Most universes would have a set of physical laws and structures that just wouldn’t allow for life to exist in that universe. Every now and then though, you’d get a universe (like ours) that has all the correct ingredients that allow for life to develop. The ratio, keep in mind, would be something ridiculous like one out of every 500,000,000 universes could form life. Point is, not many could support life, but eventually you’d find another that can as there’s no limit to the amount of universes that could exist. When you do find a universe that supports life, we can extrapolate data from our experience. Eventually, somewhere in that universe, it’s feasible that at least one intelligent species would begin. They, like us would eventually learn to develop technology. They, like us, would create something like a video game or computer program a sort of simulated universe. They, like us would get better at it. And better. And better.

They would eventually, extrapolating from the trajectory of our technical advances, create a program with simulated minds, artificial beings that think themselves real and think the games and programs they inhabit are the real world.

Would these intelligent people just create simulated, artificial program? Nope. Just like us, they’d create simulation after simulation after simulation. The ratio of simulated universes per real, inhabitable universes would be like 500,000,000 per real universe. Do the math…

The chance is, given my arbitrarily (and conservative) numbers, 1000/1 that we are not real, that we’re actually currently living in some sort of matrix reality. Wrap your heads around that motherfuckers. For every real (inhabitable) universe, there’s a thousand fake ones. This is the REAL conclusion that our ONLY unified theory of reality (general relativity and quantum mechanics) brings us to.

Is there hope? Yes. When others search for the bruise in the CMB, it’s proven to be inconsistent, undermining the reliability of this evidence. We’re essentially little better off than Square One. It’s still in the air whether or not we all live in the fucking matrix.

Juuuuuuuuuuust kidding!

…LET ME SCARE YOU WAY FUCKING MORE!

In this link you can watch theoretical physicist James Gates talking to Neil DeGrasse Tyson about a funny little discovery he made. Oh you know only that there are bits of computer code embedded in the fabric of the universe.

We talked about the antiparticles, which form antimatter atoms when combined in the same way as regular particles and regular atoms. Hydrogen atoms are one electron orbiting one proton. Antihydrogen is one positron orbiting one antiproton.

Antihydrogen was produced at CERN in 1995. This was done by making antiprotons using a particle accelerator and shooting them into xenon clusters (a bunch of xenon atoms). Only a very small number of antihydrogen atoms can be made this way.

Theoretically, there would be a lot of antimatter in the universe, and therefore a lot of antihydrogen floating out there in space. This could result in higher antimatter atoms (helium, lithium, etc), and even antimatter stars and planets. This appears not to be the case, or at least it cannot be detected if it is.